The catalytic conversion of hydrocarbons by a cyclic, generally adiabatic process, is known. Examples of hydrocarbons which are converted by these processes include the lower paraffins such as propane, n-butane, isobutane, normal and isopentane. Representative products resulting from this process include propylene, butene and butadiene, isobutene; isoamylene and isoprene. In the cyclic catalytic process, conversion of the saturated paraffin is carried out in an endothermic dehydrogenation reaction followed by an exothermic regeneration of the catalyst wherein carbonaceous deposits formed on the catalyst's surface during the hydrocarbon on-stream period are burned thereby furnishing heat required in the catalytic dehydrogenation reaction. To operate, the heat required in effecting dehydrogenation must be equal to the heat provided by the exothermic regeneration as well as other sources of heat input such as sensible heat of feed and air. Representative patents which disclose cyclic, adiabatic catalytic dehydrogenation processes for the production of olefinic materials include:
U.S. Pat. No. 2,419,997, which discloses the production of dehydrogenated aliphatic hydrocarbons in the presence of a chromia-alumina catalyst. A cyclic, generally adiabatic process, is used. A balanced heat load is achieved through the regulation of temperature or time of contact, or both, within the catalytic dehydrogenation reactor to produce a net exothermic heat value while maintaining temperature in a suitable range for dehydrogenation.
U.S. Pat. No. 2,943,067 discloses a process for catalytically dehydrogenating olefins in a cyclic, generally adiabatic process. A chromia-alumina catalyst promoted with a potassium or lithium oxide is used. The catalyst is described as being one giving good conversion and high selectivity over long periods of time. It is stated in the patent the process requires an over-all zero net heat, i.e., the endothermic reaction heat of dehydrogenation must equal the exothermic regeneration heat of coke combustion and other sources of heat input in order to avoid a runaway reaction.
U.S. Pat. No. 3,780,129 discloses a process for the dehydrogenation of aliphatic hydrocarbons to produce diolefins, the process utilizing a chromia-alumina catalyst in a cyclic, adiabatic process.
U.S. Pat. No. 3,340,321 discloses a mechanism for temperature control in a process for the dehydrogenation of aliphatic hydrocarbons to produce olefins. Temperature control is maintained by determining the coke requirement for a heat-balanced operation in the production of double bond compounds and controlling the amount of steam introduced into the bed to balance the heat load.